Semi-active Suspension Control Strategy Research Articles

Research on Two-Stage Semi-Active ISD Suspension Based on Improved Fuzzy Neural Network PID Control.

To better improve the ride comfort and handling stability of vehicles, a new two-stage ISD semi-active suspension structure is designed, which consists of the three elements, including an adjustable damper, spring, and inerter. Meanwhile, a new semi-active ISD suspension control strategy is proposed based on this structure. Firstly, the fuzzy neural network's initial parameters are optimized using the grey wolf optimization algorithm. Then, the fuzzy neural network with the optimal parameters is adjusted to the PID parameters. Finally, a 1/4 2-degree-of-freedom ISD semi-active suspension model is constructed in Matlab/Simulink, and the dynamics simulation is carried out for the three schemes using PID control, fuzzy neural network PID control, and improved fuzzy neural network PID control, respectively. The results show that compared with adopting PID control and fuzzy neural network PID control strategy, the vehicle body acceleration and tire dynamic loads are significantly reduced after using the grey wolf optimized fuzzy neural network PID control strategy, which shows that the control strategy proposed in this paper can significantly improve the vehicle smoothness and the stability of the handling.

Pointwise‐constrained optimal control of a semiactive vehicle suspension

SummaryThis article presents an optimal control strategy (OCS) for semiactive vehicle suspensions with road profile sensors. The suspension is modeled as a quarter‐car model with a magnetorheological (MR) damper. The OCS main objective is to minimize the fourth‐power acceleration of the sprung mass. In addition, three pointwise constraints of the model are taken into account when the optimal control problem is solved: suspension travel limits (upper and lower) and tyre vertical force. In order to deal with a large number of constraints, we implement the gradient optimization method based on the method of moving asymptotes routine, which shows very good performance reaching optimal controls while satisfying the constrains. The solution has been compared with two passive MR damper configurations (low and high damping) as well as Skyhook and Balance control strategies for three different road inputs. Results show that OCS fulfills the constraints and reduces the sprung mass acceleration peak and the root‐mean‐quad acceleration up to 59%, in comparison to passive strategies.

General Theory of Skyhook Control and its Application to Semi-Active Suspension Control Strategy Design

A novel general theory of skyhook control is proposed and applied to the semi-active suspension control strategy design to improve the performance of the vehicle suspension system. Based on this theory, the mechanical impedance model of the general theory of skyhook suspension is established. To design the suspension structure, the effect of the skyhook element and its parameters on suspension is analyzed. Then, adaptive fish swarm algorithm based on nonlinear dynamic visual field is used to optimize the parameters of the general theory of skyhook control. To realize the general theory of skyhook control and verify it, a novel controllable inerter is designed and utilized into the semi-active suspension system. The simulation results demonstrate that the semi-active suspension with a general theory of skyhook control can enhance the suspension performance. Finally, the robustness of the general theory of skyhook control under different spring stiffness and sprung mass is researched. The results indicate that the suspension with the general theory of skyhook control has superior performance and robustness compared with the traditional skyhook damper controlled suspension and passive suspension.

Design and Validation of a Full Body Control Semi-Active Suspension Strategy for a Supercar

Abstract The paper designs a semi-active suspension control strategy for a supercar. The control strategy aims at providing sprung mass stability in terms of heave, pitch and roll dynamics. Supercars dynamics are very demanding in that the vehicle has to provide excellent stability during pilot-induced sprung mass movements (braking, acceleration and turning) and a reasonable road disturbance isolation. The proposed control system is based on four independent modified sky-hook controllers and a centralized high-level controller that schedules the parameter of the sky-hook algorithms taking into account the driver’s input. The paper implements the proposed algorithm on an instrumented supercar and validates the approach on a number of maneuvers.

Investigation on Semi-active Suspension System for Multi-axle Armoured Vehicle using Co-simulation

<p>The objective of the study is to evaluate the performance of various semi-active suspension control strategies for 8x8 multi-axle armoured vehicles in terms of comparative analysis of ride quality and mobility parameters during negotiation of typical military obstacles. Since the cost, complexity and time precludes realisation of actual system, co-simulation technique has been effectively implemented for this investigation. Co-simulation combines advanced virtual prototyping and control technology which offers a novel approach to investigate the dynamics of such complex system. The simulations for the integrated control system along with multi body model of the vehicle are carried out for the control strategies, viz. continuous sky hook control, cascade loop control and cascade loop with ride control and compared with passive suspension system. The vehicle with 8x8 configuration is run on the real world obstacle profiles, viz. step, trench, trapezoidal bump and corrugated road and the effect of control strategies on ride comfort, wheel displacement and ground reaction is presented. It is observed that cascade loop with ride control in semi-active mode offers better vehicle ride comfort while crossing the said obstacles. The improved performance parameters are achieved through stabilisation of heave, pitch and roll motions of the vehicle through outer loop and isolation of vehicle level uneven disturbances through the fuzzy logic controller employed in inner loop.</p>

Comprehensive Analysis for Influence of Controllable Damper Time Delay on Semi-Active Suspension Control Strategies

This paper presents a comprehensive comparison and analysis for the effect of time delay on the five most representative semi-active suspension control strategies, and refers to four unsolved problems related to semi-active suspension performance and delay mechanism that existed. Dynamic characteristics of a commercially available continuous damping control (CDC) damper were first studied, and a material test system (MTS) load frame was used to depict the velocity-force map for a CDC damper. Both inverse and boundary models were developed to determine dynamic characteristics of the damper. In addition, in order for an improper damper delay of the form t+τ to be corrected, a delay mechanism of controllable damper was discussed in detail. Numerical simulation for five control strategies, i.e., modified skyhook control SC, hybrid control (HC), COC, model reference sliding mode control (MRSMC), and integrated error neuro control (IENC), with three different time delays: 5 ms, 10 ms, and 15 ms was performed. Simulation results displayed that by changing control weights/variables, performance of all five control strategies varied from being ride comfort oriented to being road handling oriented. Furthermore, increase in delay time resulted in deterioration of both ride comfort and road handling. Specifically, ride comfort was affected more than road handling. The answers to all four questions were finally provided according to simulation results.

ISO/IEC/IEEE 21451 Smart Sensor Network for the Evaluation of Motorcycle Suspension Systems

Smart sensors and transducers are being widely employed in the development of electronically controlled systems, such as advanced suspensions, to improve the performance guaranteed by terrestrial vehicles. Nevertheless, a standard reference for the full exploitation of the smart features is not yet extensively adopted. The CAN-bus is only used for the communication functionalities within a sensor network, resulting in cost-effective and more reliable connections. An original data-driven approach, based on both the CAN-bus and the IEEE ISO/IEC/IEEE 21451 standard, is proposed for the characterization of suspension systems of two-wheel vehicles with regard to the comfort and vehicle handling. Because of the ISO/IEC/IEEE 21451, the data acquired from sensor are sent by means of a GPS-General Packet Radio Service module to PC software that implements the processing algorithm. The proposed methodology includes a low-cost measurement setup, data processing algorithms in both time and frequency domain, and the introduction of model-free synthetic indices to experimentally compare the on-road behavior influenced by different damping characteristics for the suspension system. The method is applied to the on-road verification of the riding comfort assured by different control strategies for semiactive suspensions.

Study of semi-active suspension control strategy based on driving behaviour characteristics

In this paper, a semi-active suspension control system incorporating driving behaviour characteristics is presented by recognising driver behaviours on the basis of a quarter car model with a magneto-rheological (MR) damper. First, a specific driver model for recognising driver behaviours is developed to accurately recognise drivers' intentions based on driving data from vehicle sensors. Then, by changing the controllable MR damping ratio in real-time based on the outputs of the driver model, the individual driver's expectation of overall comfort or road-holding performance can be satisfied. Furthermore, simulations of the semi-active suspension control strategy with the driver model compared with the simulations without the driver model are conducted using Matlab/Simulink. The simulation results indicate that the proposed semi-active suspension control strategy with embedded driving behaviour characteristics is better suited to the driver's intentions than other control strategies.

Evaluation of semi-active suspension control strategies for 8x8 armoured vehicle using stochastic road profile inputs

This study focuses on modeling and predicting vehicle suspension response under the source of road disturbance. A simulation based numerical method has been proposed for comparison of vehicle suspension system for stochastic inputs from random road surface profiles. The road surface is considered as a stationary stochastic process in time domain assuming constant vehicle speed. Using IFFT, it is possible to generate the road surface elevations as a function of time. Time domain responses of the output of the suspension system are obtained and compared. A mathematical model has been developed and control algorithm has been verified with the purpose/objective of minimizing the unwanted sprung mass motions such as heave, pitch and roll. Semi active suspension gives better ride comfort with consumption of fraction of power required for active suspension. Comparative performance of passive suspension along with two semi-active suspension control logics namely, on-off skyhook and continuous skyhook has been demonstrated through simulations for different class of roads as defined in ISO:8608. The ride comfort is evaluated and compared in terms of r.m.s acceleration at CG in vertical direction (Z), which is the major contributor for ORV (Overall Ride Value) Measurement.

An investigation on semi-active suspension damper and control strategies for vehicle ride comfort and road holding

The real “golden age” of electronic suspension can be probably located in the 1980s; during that decade the exceptional potential of replacing a traditional spring-damper system with a fully fledged electronically controllable fast-reacting hydraulic actuator was demonstrated. High costs, significant power absorption, bulky and unreliable hydraulic systems, and uncertain management of the safety issues: the fatal attraction for fully active electronic suspensions lasted only a few years. In the second half of the 1990s, a new trend emerged: it became increasingly clear that the best compromise of cost (component cost, weight, electronics and sensors, power consumption, etc.) and performance (comfort, handling, safety) was to be found in the technology of electronically controllable suspensions: the variable-damping suspension or, in brief, the semi-active suspension. After a decade this technology is still highly promising and attractive: it has been introduced in the mass-market production of cars; it is entering the motorcycle market; a lot of special vehicles or niche applications are considering this technology; many new variable-damping technologies are being developed. Semi-active suspensions are expected to play an even more important role in the emerging trend of electric vehicles with in-wheel motors: in such a vehicle architecture the role of suspension damping is more crucial, and semi-active suspensions can significantly contribute to reduce the negative effects of the large unsprung mass. As in many other electronically controlled systems, the actuator is not “smart itself”: it simply inherits the smartness (or dumbness) of its control algorithm designer. The key of semi-active suspensions is in the algorithm. For the discussed reasons, this paper briefly reviews the basic theoretical concepts for variable-damping shock absorber technologies and the available control algorithms.

Survey and performance evaluation on some automotive semi-active suspension control methods: A comparative study on a single-corner model

In this paper, an overview and a benchmark of some semi-active suspension control strategy performances is proposed. Based on a recent result of the authors, where the optimal semi-active performance trade-off was addressed, here a complete benchmark to evaluate any controlled semi-active suspension is proposed, and applied to different control approaches. This paper aims at providing a picture – as complete as possible – of the present state of the art in the semi-active suspension control field in terms of comfort and road-holding performance evaluation and trade-off.

A Single-Sensor Control Strategy for Semi-Active Suspensions

The topic of this brief is the design and analysis of a control strategy for semi-active suspensions in road vehicles. Currently used closed-loop control strategies (like the Sky-Hook damping) require two sensors for each suspension. Typically, two accelerometers or an accelerometer combined with a stroke sensor are used. In this brief, a simple but innovative algorithm is proposed that is capable of providing quasi-optimal performance using a single accelerometer. The starting point of this work is the Mix-SH-ADD control algorithm, which has been recently developed and proposed. Starting from that idea, the single-sensor algorithm is derived. This algorithm pays a small price in terms of performance with respect to the mix SH-ADD algorithm, while guaranteeing cost reduction and augmented reliability.

A Single-Sensor Control Strategy for Semi-Active Suspensions

The topic of this brief is the design and analysis of a control strategy for semi-active suspensions in road vehicles. Currently used closed-loop control strategies (like the Sky-Hook damping) require two sensors for each suspension. Typically, two accelerometers or an accelerometer combined with a stroke sensor are used. In this brief, a simple but innovative algorithm is proposed that is capable of providing quasi-optimal performance using a single accelerometer. The starting point of this work is the Mix-SH-ADD control algorithm, which has been recently developed and proposed. Starting from that idea, the single-sensor algorithm is derived. This algorithm pays a small price in terms of performance with respect to the mix SH-ADD algorithm, while guaranteeing cost reduction and augmented reliability.

Semiactive Suspension Control of a Light Commercial Vehicle

This paper presents the design and implementation of a semi-active suspension control system for a light commercial vehicle using continuously varying dampers, accelerometers, and an onboard processor. The control algorithms such as sky-hook, ground-hook, and hybrid are designed based on the vertical velocities of each quarter of the car. These velocities are estimated from Kalman filter using quarter car vehicle model. The controllers are implemented in an actual vehicle equipped with the developed semiactive suspensions system and their performance are compared. Sky-hook control improved ride comfort by reducing body accelerations in the 1-3 Hz range, ground-hook control improved road holding by reducing wheel accelerations in the 10-15 Hz range, and hybrid control results were in between the sky-hook and ground-hook results. The main contribution of this paper is the successful implementation of the semiactive suspension control strategies on an actual vehicle with accompanying experimental results.

A new semi-active suspension control strategy through LPV technique

This paper is concerned with the design and the analysis of a semi-active suspension controller. In the recent years different kinds of semi-active control strategies, like two-state Skyhook, LQ-clipped or model-predictive control, have already been developed in the literature. In this paper, a new semi-active suspension control strategy that a priori satisfies the principal limitations of a semi-active suspension actuator (dissipative constraint and force bounds) is introduced using the tools of the linear parameter varying (LPV) theory. This new approach exhibits some interesting advantages (implementation, performance flexibility, robustness, etc.) compared to already existing methods. Both industrial criterion based evaluation and simulations on a nonlinear quarter vehicle model are performed to show the efficiency of the method and to validate the theoretical approach.

MIX-1-SENSOR: A CONTROL STRATEGY FOR SEMI-ACTIVE SUSPENSION.

The topic of this paper is the design and analysis of a control strategy for semi-active suspensions in road vehicles. Currently used closed-loop control strategies (like the Sky-Hook damping) require at least two sensors for each suspension. In this paper a simple but very innovative algorithm is proposed, capable of providing quasi-optimal performance using a single accelerometer. The starting point of this work is the mix Sky-Hook Acceleration-Driven-Damper control algorithm, which has been recently developed and proposed. Starting from that idea, the single-sensor algorithm is derived. This algorithm pays a little performance price with respect to the mix SH-ADD algorithm, while guaranteeing cost-reduction and augmented reliability. In this work the theoretical development is complemented with extensive simulation results using a 2-wheels vehicle simulator comprising an accurate modelling of the semi-active dampers. Some final experimental results are also provided.

A LPV BASED SEMI-ACTIVE SUSPENSION CONTROL STRATEGY

In this paper we consider the design and analysis of a semi-active suspension controller. In the recent years different kinds of semi-active control strategies, like two-state Skyhook, LQ-clipped or model-predictive, have already been developed in the literature. In this paper we introduce a new semi-active suspension control strategy that achieves a priori limitations of a semi-active suspension actuator (dissipative constraint and force bounds) through the Linear Parameter Varying (LPV) theory. This new approach exhibits some interesting advantages compared to already existing methods (implementation, performance flexibility, robustness etc.). Both industrial criterion evaluation and simulations on nonlinear quarter vehicle model are performed to show the efficiency of the method and to validate the theoretical approach.

Mixed Sky-Hook and ADD: Approaching the Filtering Limits of a Semi-Active Suspension

The problem considered in this paper is the design and analysis of control strategies for semiactive suspensions in road vehicles. The most commonly used control algorithm is the well-known sky-hook (SH) damping. Recently, a new control approach named acceleration driven damping (ADD) has been developed, using optimal-control theory. It has been shown that SH and ADD have complementary characteristics: SH provides large benefits around the body resonance; otherwise performs similarly to a passive suspension; instead, ADD provides large benefits beyond the body resonance. The first goal of this paper is to show that—in their specific frequency domains—SH and ADD provide quasi-optimal performances, namely, that it is impossible to achieve (with the same semi-active shock-absorber) better performances. This result has been obtained using the framework of the optimal predictive control, assuming full knowledge of the disturbance. This result is very interesting since it provides a lower-bound to semi-active suspension performances. The second goal of the paper is to develop a control algorithm which is able to mix the SH and ADD performances. This algorithm is surprisingly simple and provides quasi-optimal performances.

Acceleration-Driven-Damper (ADD): An Optimal Control Algorithm For Comfort-Oriented Semiactive Suspensions

Abstract The problem considered in this paper is the design and analysis of control strategies for semiactive suspensions in road vehicles. The most commonly used control framework is the well-known Sky–Hook (SH) damping. Two-state or linear approximation of the SH concept are typically implemented. The goal of this paper is to analyze the optimality of SH-based control algorithms, and to propose an innovative control strategy, named Acceleration-Driven-Damper (ADD) control. It is shown that ADD is optimal in the sense that it minimizes the vertical body acceleration (comfort objective) when no road-preview is available. This control strategy is extremely simple; it requires the same sensors of the SH algorithms, and a simple two-state controllable damper. In order to assess and to compare the closed-loop performance of the SH and ADD control strategies, both a theoretical and a numerical analysis of performance are proposed.